An ESXi host is marked with an alarm stating "ESXi Host Certificate Status" when the host certificate is nearing or past its expiration date.
vCenter Server monitors all the certificates within the VMware Endpoint Certificate Store. It triggers a Certificate Status alarm within the vCenter Server if any certificate is close to its expiration date.
Renew the affected ESXi Host's SSL certificate
For self-signed certificates
Renew an ESXi host certificate using the vSphere UI directly to a host or on the vCenter Server:
If you are unable to manage affected ESXi host from vCenter Server vSphere UI, renew ESXi host certificate using SSH session:
$ /sbin/generate-certificates
$ /etc/init.d/hostd restart && /etc/init.d/vpxa restart
For custom CA certificates see the knowledge base article at Configuring CA signed certificates for ESXi hosts
Prerequisites before refreshing/renewing the ESXi SSL certificates from vCenter server vSphere UI:
For more information, see Certificate Management for ESXi Hosts.